Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Simultaneous breeding and moulting reduces fitness

Brush finches fly more slowly if they are reproducing and moulting at the same time

Moulting and breeding cost birds a lot of energy. So it would make sense for the animals to do these two things at separate times. Yet slaty brush finches (Atlapetes schistaceus) in the Colombian rainforest moult and breed at one and the same time.

Life can be exhausting for the slaty brush finch: in this tropical bird species, breeding and moulting overlap. Not surprisingly, this double burden takes a toll on the bird's fitness.
© MPI for Ornithology

Scientists at the Max Planck Institute for Ornithology in Radolfzell and Princeton University therefore decided to examine whether this double burden presented evolutionary disadvantages to the tropical birds. What they found is that the wing feathers of birds that breed and moult at the same time are lighter and shorter than in birds that go through these phases consecutively. Also, their flight speed during escape flights is slower on average. This possible loss of evolutionary fitness is likely to be offset by as yet unknown positive effects.

Because feathers become continually worn down, birds regularly renew their plumage. When moulting, the flying ability of some animals can either be reduced or totally impaired, and they are less protected from the cold. Moulting also uses up a lot of energy. Birds therefore avoid other energy-intensive activities when they are moulting. So moulting and breeding usually take place separately, as they would otherwise both be competing for valuable energy reserves.

However, breeding and moulting overlap in some tropical bird species, such as some individuals in the slaty brush finch (Atlapetes schistaceus). Scientists from the Max Planck Institute for Ornithology and Princeton University therefore documented the degree of moulting and the reproductive state of these birds in Colombia on the basis of the size of their gonads and the condition of their feathers.

A comparison of feather quality revealed that moulting and reproduction do in fact compete for energy resources. "The feathers of birds that moult and breed at the same time are shorter than and almost half as heavy as those of birds that only moult. The consequence of this is smaller, less stable wings," says Maria A. Echeverry-Galvis, a colleague of Michaela Hau from the Max Planck Institute for Ornithology.

Shorter feathers and wings may have a detrimental effect on the birds' flight qualities. The ornithologists therefore measured the speed at which the birds fly off when startled. "Brush finches which are moulting and breeding at the same time fly almost 30 per cent slower than those that are only moulting or only breeding. This could make them easier for predators to catch. So simultaneous moulting and breeding means a significant loss of fitness for the brush finches," says Echeverry-Galvis.

Why some birds still moult and reproduce at the same time is something the researchers do not yet know. They suspect that unknown factors might be positively offsetting the poor quality of their feathers. Conceivably, the birds slim down when they have to transport the same weight with smaller wings – this might compensate for the loss of wing surface during moulting. "And we also discovered that brush finches that moult and breed in parallel are slightly larger on average. So maybe only big and strong individuals can handle doing both at once," says Michaela Hau.
Prof. Dr. Michaela Hau
Max Planck Institute for Ornithology (Radolfzell), Radolfzell
Phone: +49 7732 1501-13
Email: mhau@­
Related articles
Maria Angela Echeverry-Galvis & Michaela Hau
Flight performance and feather quality: paying the price of overlapping moult and breeding in a tropical highland bird

PLoS One, 9 May 2013

Prof. Dr. Michaela Hau | Max-Planck-Institute
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Novel mechanisms of action discovered for the skin cancer medication Imiquimod

21.10.2016 | Life Sciences

Second research flight into zero gravity

21.10.2016 | Life Sciences

How Does Friendly Fire Happen in the Pancreas?

21.10.2016 | Life Sciences

More VideoLinks >>>